Alloy steel of high expansion coefficient



United States Patent 2,739,057 ALLOY STEEL OF HIGH EXPANSION COEFFICIENTPeter Payson, New York, N. Y'., assignor to Crucible Steel Company ofAmerica, New York, N. Y., acorporation of New Jersey No Drawing.Continuation of application Serial No. 201,870, December 20, 1950. Thisapplication October 24, 1952, Serial No. 316,803

10 Claims. (Cl. 75-123) This invention pertains to alloy steels whichare characterized in possessing relatively high coeflicients ofexpanslon.

This application is a continuation of my copending application SerialNo. 201,870, filed December 20, 1950, now abandoned, and entitled AlloySteel of High-Expansion Coeflicient.

It is the object of the invention to provide an alloy steel having ahigher coefiicient of expansion over the range of room temperature to600 F., than is now available in known steels. A steel of this characteris required for use as high strength bolts, screws, tie rods, and otherparts in assemblies made with aluminum pieces, in order that the fitbetween the steel and the aluminum be maintained as tight as possible.As is well known, aluminum and its alloys have a much higher coeflicientof expansion for the range 70 to 600 than steel, namely about 15 10-inch per inch per degree F., as against 7.5 10- for ordinary carbon orferritic steels, and about 10.0 to 10.5 x10" for the austeniticstainless steels.

There has been available for some time a special composition of steel,of analysis,

Percent Percent Percent Percent Percent 0 Mn or M0 Bal.

50 3. 11. 0 3. 0 T5 0 E5 50 max. Fe

covered by Aeronautical Specification 5624A, which has the highestvcoefiicient of expansion of any steel so far produced, namely, about11.0 to ll.2 However, this expansion value is still far short of that ofaluminum and its alloys, and there is a demand for a steel with a higherexpansion value.

Another object of this invention is to provide a high expansion steel oflower alloy content than the high expansion steels now being used. Thisis a factor of strategic as well as of economic importance.

It is Well-known that austenitic steels have higher expansion valuesthan steels containing the transformation products of austenite, thatis, ferrite, pearlite, bainite, or martensite. Also it is well knownthat some compositions of austenite have expansion values difierent fromthose of others as shown in Table I, below, taken from data published inU. S. Department of Commerce, Circular C447, Mechanical Properties ofMetals and Alloys.

TABLE I Expansion values of some known austenitic steels Anal sis,Percent Expansion y Coefliclent torthe Range No Bal 70 to 750 0 Mn s1 NiOr Other i i ig 446..- 40 13 1s 2.5w Fe 9.8 3449..." .06 .36 .28 9.617.7 Fe 10.1 2474 .39 .74 1.12 20.2 7.9 22Gu Fe 10.5 .39 36.1 39 Cu Fe3.5 2483-.-" .42 .71 1.03 36.0 16.4 Fe 8.5

Ice

It is clear from Table I that none of these steels has a coeflicient ashigh as that of the AMS 5624A analysis given above. I

Now I have discovered that a steel of relatively low nickel content,that is, about 6 to 13% with enough carbon and manganese in it tostabilize the austenite of the steel, and containing practically nochromium, has a higher coefiicient than steel of the AMS 5624A analysis,and. so far as is known, higher than any other steel pre- 0viouslyknown.

The steel of my invention contains according to the broad range ofanalysis, about .40 to 1.00% carbon, about 3.0 to 13.0% manganese andabout 6 to 13% nickel, the sum of nickel and manganese beingpreferablyat least 11%, and the balance being substantially all iron with usualimpurities, although the steel may include optional additions of up toabout 2.0% in aggregate of one or more of the elements Si, V, Mo and W,and a maximum of 0.5%.Cr1 In the annealed condition, that is, as air 0cooled from about '2100 F., this steel has a coefficient of expansion of12.0 10* inch per inch per degree F. for the range 70 to 600 F. Withinthe limits of composition, just given, the value of the expansioncoefficient of the steel is practically unaffected by composition 25changes as may be seen in Table II.

TABLE II Steels of this invention which as annealed have a coefiicientof expansion value over the range from 70 to 600 F. of about 12.0 10inch per inch per degree F.

Analysis, Percent 5 Bar 3 0 Mn Si Ni Or Bal.

55 5. 2 11 6.1 0. 09 Fe .69 9.1 .11 6.1 0. 02 Fe .68 12.9 .13 6.0 0. 02Fe .59 5.3 .31 8.9 0.05 Fe .57 8.8 .33 8.8 0.07 Fe .66 12.8 .18 9.0 0.02Fe 4. 9 05 11. 9 0. 03 Fe .69 9.2 .13 13.0 0.01 Fe .61 4.8 .71 12.1 0.20Fe .73 13 6 .16 12.9 0.00 Fe TABLE IH Efiects of high nickel andchromium on the expansion coefiicient 0f austenitic steels [All samplestested as annealed, 1. 9., air cooled from 2100 F.]

Analysis, Percent Expansion fCoetiicienZB or ran 6 to 600 F.

0 Mn' Si N1 Or Bal. In. per in. X 10- per F.

. 61 4. 8 71 12. 1 0 2 Fe 12.0 58 5. O 53 13.8 4 9 Fe 11. 1 58 5. 1 6115. 8 0 1 Fe 11. 7 62 4. 9 59 16. 1 3 4 Fe 11. 0

It is clear from these data and thoseot TablelI, that 65 chromium has amarked eliect on the expansion coefiicient, causing it to be decreasedappreciably; and that nickel upwards of about 13% causes the steel tohave a lower expansion coeificient than a steel containing nickel withinthe range of the present invention, i. e., 6 to 13%. Since the steel ofthis invention is austenitic and therefore cannot be hardened except bycold working; and

TABLE IV ponents having high expansion coefiicients, said fasteningelement being madepf a work hardened austenitic alloy steel having ahardness of at least Rockwell C 28, and having a c oefiicient ofexpansion at least 11.8 10- 5 inch per inch per degree F., said steelcontaining: about 0.4 to l.0 -carbon; about; to 13% nickel, and about 3to 14% manganese, flie'sum of nickel and manganese being'at least 11%upto about 0.5% chromium; up to about 2% in aggregate of at least oneelement selected 10 from the group consisting of silicon, vanadium,tungsten Efiect of composition on the expansion coefi'icient ofaustenitic steels after cold working [Samples tested both as annealed,i. 9., air cooled from 2,100 F., and as cold worked about 22% from theannealed condition] Anal sis ercent Expansion y p Hard' M ti 1 vii i11658, B Q C rum 0 Rock- Sus c ptJ 600%. m.

0 Mn s1 Ni well per 1n. 10

per F s. 2 11 6.1 Annealed.-." B76 N. M. 12.0 5. 2 11 6.1 Cold Worked.on; M. 11.6 9.1 .11 6.1 Anne e B81 N.M. 12.0 9.1 11 6.1 Cold Worked. cs5VSM 12.0

1 N. M.non magnetic; M.magr1etic; VSM-very slightly magnetic.

On the basis of these data a steel in accordance with the invention butof higher alloy content than the minimum, should be used whenever thesteel is to be cold worked or is to be subjected to very lowtemperatures which might tend to cause appreciable transformation of theaustenite.

The preferred range of composition of the steel of this invention is:.50 to .70% carbon; 5.0 to 9.0% manganese; up to 1.0% silicon; up to0.5% chromium; 6.0 to 10.0% nickel; up to 2.0% in aggregate of otherelements not detrimental to the high expansion properties of the steel;balance iron.

Especially useful analyses are those of Table V below.

I claim:

1. A forgeable, austenitic alloy steel, characterized in having acoeflicient of expansion of at least 11.8)( inch per inch per degree F.,over the temperature range of about 70 to 600 F., said steel containing:about 0.5 to 0.7% carbon; about 6 to 10% nickel; about 5 to 9%manganese; up to about 0.5 chromium; up to about 1% silicon; up to about2% in aggregate of other elements which do not impair the highcoefficient of expansion of the steel; and the balance iron.

2. A forgeable, austenitic alloy steel, characterized in having acoefficient of expansion of at least 1l.8 lO'" inch per inch per degreeF., over the temperature range of about 70 to 600 F., said steelcontaining: about 0.5 to 0.7% carbon; about 6 to 10% nickel; about 5 to9% manganese; up to 1.0% silicon; and the balance iron.

3. A fastening element for uniting structural comand molybdenum; and thebalance substantially all iron.

4. A fastening ,element for uniting structural components havingln'ghexpansion coefficients, said fastening element being made of a workhardened austenitic alloy steel having. a hardness of at least RockwellC 28, and having a coefiicient of expansion of at least 11.8X 10- inchper inchper degree B, said steel containing: about 0.5 to 0.7% carbon;about 6 to 10% nickel; about 5 to 9% manganese; up to about 0.5%chromium; up to about 1% silicon; up to'about 2% in aggregate of otherelements which do not impair the high coefiicient of expansion of thesteel; and the balance iron.

5. A fastening element for uniting structural components having highexpansion coefficients, said fastening element being made of a workhardened austenitic alloy steel having a hardness of at least Rockwell C28, and having a coeflicient of expansion of at least ill-3X10- inch perinch 'per degree F., said steel containing: about 0.4 to 1.0% carbon;about 6 to 13% nickel, and about 3 to 14% manganese, the sum of nickeland manganese being at least 11%; up to 1.0% silicon; and the balanceiron.

6. A fastening element for uniting structural components having highexpansion coefl'icients, said fastening element being made of a workhardened austenitic alloy steel having a coeflicient of expansion of atleast 1l.8 l0- inch per inch per degree F., said steel containing: about0.5 to 0.7% carbon; about 6 to 10% nickel; about 5 to 9% manganese; upto 1.0% silicon; and the balance iron.

7. A forgeable, austenitic alloy steel, characterized in having acoefiicient of expansion of at least 11.8 l0- inch per inch per degreeF., over the temperature range of about 70 to 600 F., said steelcontaining: about 0.55 to 0.65% carbon; about 5 to 6% nickel; about 8 to9% manganese; about .20 to 1% silicon; and the balance ll'OIl.

8. A forgeable, austenitic alloy steel, characterized in having acoeflicient of expansion of at least 1l.8 10 inch per inch per degreeF., over the temperature range of about 70 to 600 F., said steelcontaining: about 0.55 to 0.65% carbon; about 7 to 8% nickel; about 7 to8% 70 manganese; about 0.20 to 1% silicon; and the balance iron.

9. A forgeable, austenitic alloy steel, characterized in having acoeificient of expansion of at least 1l.8 l0- P inch per inch per degreeF., over the temperature range of about 70 to 600 B, said steelcontaining: about 5 0.55 to 0.65% carbon; about 9 to 10% nickel; about 5to 6% manganese; about 0.20 to 1% silicon; and the balance iron.

10. A forgeable, austenitic alloy steel, characterized in having acoefiicient of expansion of at least 11.8 10 inch per inch per degreeF., over the temperature range of about 70 to 600 F., said steelcontaining: about 0.55 to 0.65% carbon; about 11 to 12% nickel; about 4to 5% manganese; about 0.20 to 1% silicon; and the balance lI'OIl.

References Cited in the file of this patent UNITED STATES PATENTS452,494 Fessenden May 19, 1891 1,843,903 Scott Feb. 2, 1932 1,902,589Scott Mar. 21, 1933 2,217,422 Scott Oct. 8, 1940 2,220,690 StupakotfNov. 5, 1940 FOREIGN PATENTS 7,422 Great Britain Apr. 3, 1897 MetalProgress, November 1931, pages 69 to 72.

The Book of Stainless Steels, 2nd edition, Thum, published 1935 by theA. S. M., Cleveland, Ohio; page 340.

Alloys of Iron and Chromium, High Chromium, vol. 2, page 289. Edited1940 by Kinzel and Franks.

Cold Working of Metals, page 2. Published in 1949, by the AmericanSociety for Metals, Cleveland, Ohio.

Symposium on Effect of Temperature on the Properties of Metals,published jointly (1931) by the ASTM and ASME (New York); pages 693 and694 are particularly pertinent in paper on Thermal Expansion of Metalsby Mochel.

Revue de Metallurgie, Memoires, Tome 2, 1905, pages 827-833.

1. A FORGEABLE, AUSTENITIC ALLOY STEEL, CHARACTERIZED IN HAVING ACOEFFICIENT OF EXPANSION OF AT LEAST 11.8X10-6 INCH PER INCH PER DEGREEF., OVER THE TEMPERATURE RANGE OF ABOUT 70* TO 600* F., SAID STEELCONTAINING: ABOUT 0.5 TO 0.7% CARBON; ABOUT* 6 TO 10% NICKLE; ABOUT 5 TO9% MANGANESE; UP TO ABOUT 0.5 CHROMIUM; UP TO ABOUT 1% SILICON; UP TOABOUT 2% IN AGGREGATE OF OTHER ELEMENTS WHICH DO NOT IMPAIR THE HIGHCOEFICIENT OF EXPANSION OF THE STEEL; AND THE BALANCE IRON.